Pneumatic tire

Abstract

Provided is a pneumatic tire. A belt cover layer made of an organic fiber cord spirally wound along the tire circumferential direction is provided on the outer circumferential side of a belt layer in a tread portion, and a polyethylene terephthalate fiber cord of which the elastic modulus under a load of 2.0 cN/dtex at 100° C. is in the range of 3.5 cN/(tex·%) to 5.5 cN/(tex·%) is used as the organic fiber cord. The coating rubber covering the organic fiber cord contains one or more of natural rubber, styrene-butadiene rubber, or butadiene rubber as a rubber component. The coating rubber is formed of a rubber composition in which the content of natural rubber in the rubber component is 50 mass % or more, and 5.0 parts by mass to 9.0 parts by mass of zinc oxide is blended per 100 parts by mass of the rubber component.

Description

TECHNICAL FIELD[0001]The present technology relates to a pneumatic tire using polyethylene terephthalate (PET) fiber cords in a belt cover layer.BACKGROUND ART[0002]Pneumatic tires for a passenger vehicle or a light truck typically include a structure in which a carcass layer is mounted between a pair of bead portions, a plurality of belt layers are disposed on an outer circumferential side of the carcass layer in a tread portion, and a belt cover layer is disposed on an outer circumferential side of the belt layer, the belt cover layer including a plurality of organic fiber cords spirally wound along a tire circumferential direction. In this structure, the belt cover layer contributes to the improvement of high-speed durability and also contributes to the reduction of mid-range frequency road noise.[0003]In the related art, nylon fiber cords are mainly applied to the organic fiber cords used in the belt cover layer; however, it has been proposed to use polyethylene terephthalate fi...

AI Technical Summary

Benefits of technology

[0006]As a result of diligent research on a pneumatic tire equipped with a belt cover layer made of PET fiber cord, the present inventor achieved the present technology by finding that the fatigue resistance and the suppression effect of the cord suitable for the belt cover layer can be obtained by optimizing the dip treatment of PET fiber cord and setting the elastic modulus under a load of 2.0 cN/dtex at 100° C. to be within a predetermined range. That is, in an embodiment of the present technology, a PET fiber cord of which the elastic modulus under the load of 2.0 cN/dtex at 100° C. is in the range of is 3.5 cN/(tex·%) to 5.5 cN/(tex·%) is used as the organic fiber cord constituting the belt cover layer. Thus, the road noise can be effectively reduced while satisfactorily maintaining durability of the pneumatic tire.

[0007]Further, coating rubber which contains one or more selected from natural rubber, styrene-butadiene rubber, and butadiene rubber as a rubber component, and which is formed of a rubber composition in which the blended amount of natural rubber in the rubber component is 50 mass % or more, and 5.0 parts by mass to 9.0 parts by mass of zinc oxide is blended per 100 parts by mass of the rubber component, is used as the coating rubber covering the PET fiber cord. Thus, the high-tempera

Problems solved by technology

However, the PET fiber cord tends to generate heat more easily than the conventional nylon fiber cord, and in p

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